180 gal. is more realistic, I'd be sure to reseach a few things before making a buy.
1st being the word "intolerrant" which I believe is the word they use to describe the Red Devil's tankmates............in other words they attack any perseved threat relentlessly. The devil hopefully will only take take 75 gallons of tank space in a 180 and call it his own. I'd look towards smaller meaner substrate dwellers myself like a few Salvini and Convicts and maybe an open water cichlid like a Wolf might work but the Jag is alot more territoral. I might be wrong each fish is different they'll let you know who stays and who goes.............stir clear of festae especially in pairs they'll want 100 + gallons. As for the rest of the fish mentioned as overly aggressive I have Zero experience with grammodes,black nasty,umies.etc....